1. Field of Invention
The present invention is generally related to comminuting (grinder) apparatus, and more specifically to a combination small-scale tub grinder and wood chipper and specific features that improve such apparatus.
2. Description of the Prior Art
Grinding grains, corn, hay, forage, and roughage products for more effective and digestible livestock feed is an old and well-known process. There are many kinds of machines for grinding or comminuting such products, including, for example stone mills, burr mills, hammer mills, roller mills, and others. Because of the fibrous and stalky, nature of hay, straw, and other roughages, hammer mill type grinders are generally considered to be the most effective for comminuting these forage or roughage materials; however, handling and feeding hay into a hammer mill in a uniform manner without much tedious manual labor has presented problems.
In the last two or three decades, machines generically known as tub grinders have become popular for comminuting hay, straw, and other roughages, because they are designed to feed very large bales of hay into hammer mill apparatus without excessive manual labor. In such tub grinders, the bales of hay or other roughage material are gradually fed into a hammer mill by a large rotating tub. The hammer mill is positioned on the floor or bottom of the tub, and the rotating tub rotates the bottom of the bale over the hammer mill. The hammers on the hammer mill rotating at a high angular velocity chew off the hay on the bottom of the bale as the bales rotates over the hammer mill in the floor of the tub. Typical examples of such tub grinders are shown in the following patents: U.S. Pat. No. 2,659,745, issued to W. Wortman; U.S. Pat. No. 3,615,059, issued to E. Moeller; U.S. Pat. No. 3,743,191, issued to R. Anderson; U.S. Pat. No. 3,912,175, issued to R. Anderson; U.S. Pat. No. 3,966,128, issued to J. Anderson, et. al.; U.S. Pat. No. 4,003,502, issued to E. Barcell; U.S. Pat. No. 4,087,051, issued to C. Moeller; and U.S. Pat. No. 4,106,706, issued to H. Burrows.
Such tub grinders are effective, but they are very large and relatively expensive machines that require high-powered tractors or stationary engines for sufficient power to operate them. This situation leaves smaller scale livestock feeding operators and hobby livestock feeders, who typically have only low horsepower tractors and limited funds, without any effective hay comminuting capability other than perhaps hand-feeding hay into smaller hammer mills.
While the solution to this problem at first glance appeared to be merely reducing the conventional large tub grinders in scale, it was really not so simple. Many components of large tub grinders that function well with large bales and powerful tractors do not function so well with small bales and limited horsepower. For example, a hammer mill rotor cannot be scaled down so small that it has insufficient weight and inertia, even if the tub is scaled down to handle conventional, man-sized square or round bales. Yet, a smaller tub cannot accommodate a larger hammer mill in the same manner as a larger tub can. Further, even though hay bales can be smaller in size, the hay is the same and is just as tough as hay in large bales to grind. Therefore, in a directly scaled down tub grinder and/or using smaller horsepower tractors, uneven feeding and jamming, as well as slugging the hammer mill and overloading the tractor engine result in nonuniform product and a generally frustrating experience for the operator.
Also, most small-scale operators and hobbiests really cannot afford to have separate grinding machinery for comminuting hay and for milling corn and other feed grains. It is much preferred to have a single machine that can handle roughage, such as hay and straw, as well as all kinds of grains and corn. However, the conventional tub grinders for hay cannot handle grains effectively, while the conventional hammer mills for grains cannot handle hay effectively without laborious and time consuming hand-feeding.
Still further, many small-scale operators also have need for wood chipper machinery for comminuting brush cleared from wooded areas or branches pruned from orchards and trees. Disposal of such brush and branches is easier when they are reduced to chips. There are also a number of beneficial uses for wood chips, such as bedding for livestock, mulch in gardens and around ornamental shrubbery, decorative ground coverings, and the like. Again, however, most small-scale operators cannot afford, or cannot justify economically, owning a separate wood chipper machine, even though they need one on a regular basis.
Prior to this invention, therefore, there was a significant need for a smaller-scale hammer mill machine that could be driven by a small horsepower tractor and that still had the capability and versatility of effectively handling and comminuting both hay and all kinds of corn and feed grains, as well as having the ability to comminute brush and branches into wood chips.